chemicals and synthetics used in making denim

These days, cleaning up the denim supply chain focuses mainly on water and energy use.  However, that misses a big part of denim jeans' environmental footprint. A lot of chemicals go into making a pair of jeans. 

At every step of the production chain, chemicals are inserted to facilitate some sort of process. Synthetic petro-chemicals are added in the spinning process to make the cotton stretchier. The dye bath, which is one of the most chemical intensive steps, contains all sorts of dye fixatives, oxidizing agents, reducing agents, and enzymes to bind the synthetic dye to the cotton. To get the yarns stiff enough to run through the loom, the material is sized with PVA, resins, and waxes. After the fabric is woven, the desizing process uses acids and enzymes to dissolve those chemicals that are coating the yarns, which are washed  out into the wastewater stream. And in the final step, heavy bleaches and lightening agents are used to create fades and finishes, to give that "worn in" look.  

These chemicals help give denim jeans the look and feel that the customer wants, and often can help reduce the amount of water and energy needed to dye and process the cotton. At the same time, these chemicals are harmful to the workers who grind it and breathe it, and when not treated properly, will pollute and change the pH of water systems in the surrounding community. Furthermore, there have been few studies conducted to affirm the safety of chemicals on this material after prolonged contact with the wearer's skin. 

In the graphic, customers can now put a name to some of the chemicals used in the making of their jeans. Some of these chemicals have been vetted by by standardization organizations as safe, if treated properly. Others are more dangerous in high volumes. At SOURCE Denim, we are working with environmental organizations like Greenpeace to detox the production process of our denim, and work towards the international goal of Zero Discharge of Hazardous Chemicals. 

Coming up next week...how SOURCE Denim's chemical profile is different than conventional jeans!

Our eco-friendly denim has arrived

Our first batch of denim arrived today. It's been a long, arduous process to try to find the best denim supplier out there. Our standards for "best" are different than other companies. For us, best means that a supplier is committed to cleaning up the whole process of denim production, and ensuring that the textiles it produces, as well as the working environment it maintains is as safe and healthy as humanly possible. Best also means that the manufacturer makes a kick ass product. We were looking for a denim that would inspire us to create beautiful things. Denim should have strength woven into its fibers, and a richness in color and texture that is the hallmark of good denim.

For the first three months, we were talking back and forth with a Brazilian company who claimed to have produced completely natural, chemical-free denim. They claimed that their cotton came from 60 farming families in Brazil and Peru, and that their dyeing process used no chemical auxiliaries. And it was true, the smell of their material did carry the smell of ferment that we had experienced in our own organic indigo bath. Unfortunately, though they had Brazilian certification to prove the organic origin of their cotton, they could not provide any information about their dyeing process and the chemicals that went into the production. Further digging revealed that the company was not even manufacturing the denim in-house, but had been outsourcing it with a manufacturer that had since gone bankrupt. Another casualty in the world of sustainable fashion, and hopefully one that they will be able to bounce back from. For SOURCE, the lack of communication, transparency and information on material inputs was enough for us to start looking for other suppliers.

That search led us to India, and to Italy. A large denim manufacturer in India with strong ties with Europe and one notable client in the US seemed to be a good contender. The representative for the denim product lines was forthcoming on the phone, and spoke about the many eco-friendly denim offerings they had available. They produced denim using the Clariant Advanced Denim technology, said to cut 92% water, 30% energy, and 87% cotton waste through its Pad/Sizing Ox Process. The company also produced denim with plant-based indigo, though the chemical auxiliaries and caustic agents were the same as conventional denim. They could produce textiles with both BCI (Better Cotton Initiative) or organic cotton, though he was quick to point out that organic cotton often consumed more water. He also mentioned the company was underwent self-evaluation based on the Higg Index, a tool used to help companies evaluate the environmental impact level of their supply chain. They were fast and efficient with their communication as well as delivery of samples. Their work in improving their denim value chain was admirable, though the eco-friendly element of their denim seemed to be just another one of their many product offerings. 

At the same time, we were also talking to the head of a small premium denim manufacturer based in Milan, Italy. Self described as a company "focused our production on Real Sustainable Denim with particular attention towards avoiding the utilization of chemicals and reducing water consumption", they are the first and only (as of writing) denim manufacturer to have signed on to the Detox campaign led by Greenpeace. An earnest exchange proceeded between us, as the head of the company excitedly shared his company's process and innovations on sustainable denim manufacturing. The cotton they use comes from the USA, Greece, and West Africa, with 20% of it categorized as BCI cotton.

Their dyeing process uses DyStar pre-reduced liquid indigo. We expressed some hesitation at the dye being a synthetic colorant, but he came back immediately and told us that this was the most sustainable way to dye denim, as plant-based indigo required a lot of water and chemicals to force the reduction and fix the dye to the fabric, and could not achieve the depth of color that was expected of modern denim. Using the DyStar pre-reduced indigo, it not only cut down on the transport necessary, but also required 60% less hydrosulfite and caustic soda as compared with normal synthetic or plant-based dyes. 

The most exciting thing about this denim was its use of chitosan in the weaving process. Developed by an Italian research firm, chitosan, a completely natural, non-toxic and biodegradable material derived from the discarded waste of fishing companies, is incorporated into the weaving process of the cotton yarns. The coating of chitosan eliminated the use of harmful PVA (similar to latex), which in typical denim production is used for "sizing" to stiffen the yarns for weaving and then has to be washed from the yarns using harsh chemicals and creating harmful water pollution. Because fabric no longer needs to be washed and dried after weaving, it eliminates a significant portion of water use and energy consumption for every meter of fabric. Because chitosan naturally coats and protects the dye on the yarns, there is no need for toxic fixing agents or mercerization with caustic soda and acetic acid, and again, less water and energy consumption. In total, the use of chitosan in the weaving results in 50-80% less water and 40-60% less energy consumed to produce each meter of material. "These are only a few points that we can discuss," the head of the company told me knowingly, "the rest are industrial secrets."   

All of these initiatives have allowed the denim supplier to be closer to reaching 100% of the targeted Zero Discharge of Hazardous Chemicals commitment, even earlier than 2020. Not only that, but the company has invested 2.5 million euros in a cogeneration plant and has proclaimed a reduction of their carbon emissions by 6,500,500 kg since the start of their environmental campaign. 

The enthusiasm and genuine earnestness this company had for revolutionizing the denim production process for the betterment of the world won us over. Though on paper, both the Indian and the Italian supplier produced denim that had some environmental improvements (especially in water and energy) and some environmental drawbacks (synthetics), the latter seemed to have the most heart. So we placed our first denim order with them. 

And within days, we were overjoyed that we did. Bolts of wrapped denim arrived on our doorstep, and we laid it out on the table with breathless anticipation. Peeling away the tape, the denim was slowly revealed. The rich dark blue with the slightest hint of slub was mesmerizing, and running our hands across it it was hard and strong, yet smooth. At 11.5 ounces, it was beautiful.  

  

 

What is "greenest" thread?

We compromised on thread today. For weeks we had been banging our heads against a wall. We were deliberating between 100% cotton thread, cotton wrapped polyester core thread, 100% polyester thread, and nylon thread. None of them were perfect. 

Our first inclination had been to go with cotton thread, organic if we could find it. Using cotton thread would allow us to maintain the biodegradability of the jeans at the end of its life, and would be more of a natural material. But organic cotton thread were only readily available in Tex sizes that were less than 30, suitable only for t-shirts and knits. Conventional cotton thread didn't come much larger than that, and the one Tex-90 thread that we were able to order, called "gassed cotton", ended up being closer to cotton string and would fray and snap in the machine. In general, cotton thread would prove to be weaker than any polyester thread, prone to wearing and breaking and compromising on the longevity of the garment. 

What about recycled polyester then? The big thread manufacturers Guetermann, Coats, and American & Efird did carry a recycled poly thread under different names. Guetermann (which is apparently now owned by American & Efird) produced a thread with the moniker rPET, available in their existing lines of Sew-All Thread and Mara 100. Unfortunately, the largest sizes available were Tex 30. Coats carried an ecoVerde thread, but only at Tex 35 and seemingly not readily available. American & Efird had a recycled poly thread called Wildcat Repreve, which also only went up to Tex 35, and an organic cotton thread called Anecot Organic which was available in Tex 70 and 105.

Unfortunately, there was no Anecot Organic currently available in the US. The A&E representative told me that the organic thread was produced in India, and due to lack of demand, could only be made to order, with extremely high minimums. Furthermore,  they would not be able to organically dye the thread. As we ended the conversation, he added, "You know, we also carry a 100% cotton thread, which is produced in the US with a long staple fiber and, though it's not organic, it is 100% cotton. A lot of customers who come to us initially asking about the organic thread end up purchasing just the cotton thread because they realize the organic stuff is prohibitively expensive and it doesn't come in any colors." Another blow to the sustainability entrepreneurs.  

With the need to start pushing out product, we decided on purchasing A&E D-Core thread that another company had in overstock, so that at least we were helping to reduce the burden of waste rather than produce virgin material.  D-Core is one of the best options out there for denim, as it is a cotton wrapped thread with a poly core. The core adds strength and resilience to the thread while the cotton adds natural fade and softness to the surface. Combining the two worlds, this thread is one of the most often used threads in the premium denim market. 

Nevertheless, we aspire to find a thread supplier whose materials are 100% biodegradable, with the tensile strength to take on all that we put our jeans through. 

In search of environmentally friendly zippers

It's always mind boggling for us to discover that even within the smallest, most seemingly trivial of details, the options are so innumerable that we were paralyzed by information and choice. Within the realm of zippers, there are thousands of options. As one employee at YKK Zippers put it, "If I were to send you a price list, it would be a million pages long." 

Luckily (or unluckily?) the choice for zipper manufacturers in the world can be more or less narrowed down to a small handful of manufacturers. The one that leads the industry is the all-pervasive YKK. YKK, an acronym named after its Japanese founder, essentially has a monopoly on the zipper industry worldwide. And if you've never heard of them, you could probably look down at your jeans, backpack, or sweatshirt zipper and find the tiny letters stamped on each dangling pull.

YKK has managed reign over the zipper manufacturing industry thanks to their proprietary machines which were birthed when the founder made a few alterations to existing machines back in ____. These machines (and subsequent improvements) remain the reason why cheaper knock-off zippers snag, crack, and break while YKK stays strong and sturdy. 

We may not have the secrets to YKK's magical machines, but there is enough information out there for us to learn about what goes into a zipper, which can be broken up into:

  • Pull Tab dangling handle typically made out of metal or plastic.
  • Slider Body apple-shaped piece that slides along the teeth.
  • Teeth or Chain the interlocking part that holds things closed. Can be coiled zipper, otherwise known as a self-repairing zipper made with one long spiral of extruded nylon, or in the case of jeans, a tooth zipper with metal or molded plastic teeth.
  • Tape fabric that allows the zipper to be attached to fabric. It is usually made out of polyester, but other synthetic fiber, vinyl, or cotton tape are also available.  
  • Retainer Box heat sealed plastic that prevents fraying.
  • Stops rectangular pieces at the ends of the zipper to prevent the slider from falling off.

Metal zippers can be made of aluminum or brass (a combination of copper and zinc), some with a chemical treatment to give the appearance of antique metal or a black matte finish. 

Environmental Issues

The supply chain of a zipper involves quite a number of chemical and carbon intensive processes. There are the environmental effects of extracting petrochemicals for polyester and polyamide (nylon) production as well as smelting metal. The zipper production process may involve four of the eleven priority chemicals outlined by the Zero Discharge of Hazardous Waste Group, including Alkylphenol Ethoxylates/Alkyphenols (APEOs/APEs), Per- and Polyfluroinated Chemicals (PFCs), Phthlates, and Organotin Compounds. And some Volatile Organic Compounds such as toluene and xylene are contained in paint and adhesive agents. The polyester used in most zippers prevent them from being fully biodegradable, and the blend with natural fibers often prevents them from being recyclable. 

So what zippers are out there for the sustainable, conscious consumer? YKK has made some visible strides to attempt to address the environmental impact of its products. It has signed on with bluesign, ZDHC commitment towards zero discharge by 2020, has signed on to use the Higg Index to assess 20 of its factories, performs 70-80% wastewater recycling in China and Korea, and is in the process of adopting quick dyeing technologies to reduce water and energy use. In addition, it's Japan headquarters have come out with two lines of eco-friendly zippers.

Under the trademark Natulon, YKK produces one zipper that utilizes a chemically recycled polyester (PET) in its zipper chain and slider and can be iteratively recycled, as well as one that has only the open metal pull made with recycled plastic bottles. YKK Japan had previously made a biodegradable corn-based zipper product called reEarth, though it is no longer listed in its catalog. 

Lampo, a high-end zipper company based in Italy, has an entire page touting its sustainability gains, including reclaiming 60% of its nylon used in molded zippers, recycling brass, and downcycling its zing, cotton, and polyester waste. It has recently opened a plating facility that claims to a 30% reduction in water consumption and has equipped one of its weaving facilities with photovoltaic panels, saving 23 tons of carbon dioxide annually. 

Hong Kong-based TYT claims that its Greengear zipper line is made of 100% recycled polymer. 

The most sustainable option for zippers is to reclaim them from old clothes and reuse them in garments. This is time intensive, though, as removing zippers involve wrestling with tight stitches to avoid shredding the tape. Some sellers on Ebay and Etsy sell bundles of salvaged zippers for the DIYer. 

If your zipper breaks because the slider or pull tab come off, a little company based in Oregon called zipperrescue.com provides a kit that can help you fix your zipper. Or you can figure it out yourself by buying new zipper sliders online or at a sewing shop and following instructions on Lifehacker